A broadband nondispersive cross polarization converter (CPC) structure using metasurface for far infrared region has been proposed in this article. The structure is transmittive in nature, which converts a linearly polarized incident wave to its mutually orthogonal linearly polarized wave over a band of frequency ranging from 10.25 to 22.7 THz maintaining a high polarization conversion ratio (PCR) of more than 0.95. The fractional bandwidth of 75.6% corresponding to the center frequency of PCR bandwidth having more than 0.9 PCR value has been realized. The structure is also studied for oblique incidences where it shows wide band polarization conversion up to 45° for both TE and TM polarized oblique incident waves. The electric field distributions at the top and bottom surfaces of the structure close to the center frequency of polarization conversion bandwidth indicate the orthogonal rotation of incident linearly polarized wave at the frequency of interest. For the given set of media interface a separate study on polarization conversion through Brewster angle concept has been carried out simultaneously. The structure exhibits high PCR by maintaining the compactness in thickness (~ λ/5) as well as periodicity (~ λ/3) compared to the existing reported ones.

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The theory of absorption of infrared radiation based on the formation of antiparallel surface current in a metamaterial absorber appears to be invalid when the thickness of the dielectric material in the structure is increased by an integral multiple of a half-wavelength. The absorption characteristics repeat themselves with an increase of each integral multiple of a half-wavelength, despite the fact that the surface current components for an odd value of integers are parallel to each other. This contradicts the theory of absorption based on the formation of antiparallel surface current. The reason for this uncertainty in surface current has been well explored in this paper, wherein we demonstrate theoretically the principle of absorption in a metamaterial structure based on the principle of multiple reflection and the interference model. For validation of the occurrence of the multiple reflection phenomena involved in absorption, time-domain analyses of metamaterial absorbers under normal as well as oblique incidence have been simultaneously analyzed. The time of occurrence of each reflection obtained numerically using the inverse chirp-Z transform is found to be in good agreement with the results obtained analytically.

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This paper presents successive studies of single-, double-, and triple-layered metasurface-based bandpass filters along with their equivalent circuit modeling and mathematical analyses. A triple-layered bandpass filter operating in the THz region is reported exhibiting flattop passband response while maintaining transmission of more than 95% over the entire passband starting from the design of a single-layered bandpass filter configuration. A stepwise mathematical analysis is carried out for the single-layered structure and compared with the simulation data, where the two results have been found in good agreement. Thereafter, the study is extended for double- and triple-layer bandpass filters. The triple-layered structure offers a very steep transition between passband and stopband with noise-free background, and thereby offers a potential candidate for 6G communication.

A novel compact coplanar waveguide (CPW)‐fed zeroth‐order resonator (ZOR) is reported in this article. The zeroth‐order mode is required to reduce the resonator's size. The composite right/left handed transmission line (CRLH TL) structure is designed on a single layer via‐less CPW‐fed, which reduces the fabrication complexity and makes the structure more feasible. The resonator has a compact size of 21.6 × 5.2 mm2. The measured insertion loss and return loss of the resonator are −0.72 dB and −21.3 dB, respectively at the resonant frequency, 2.80 GHz. The performance of the proposed ZOR is compared with the previously reported ZORs. All the performance parameters of the resonator are evaluated by full‐wave electromagnetic simulator IE3D, based on the method of moments (MoM) and all the results are verified by measurement. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2576–2580, 2015

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